Where have all the angry young men and women gone? You'd be hard-pressed to find them in Edinburgh, where people seem to be either busy writing rom-coms or retreating into Edwardian fantasy. Marx may have identified religion as the opium of the people, but charm is the opiate of choice for the theatre-going classes, particularly on this year's fringe.

Which brings us to Beulah, a two-hander written by Alexander Wright (who penned The Boy James about JM Barrie for Belt Up), inspired by William Blake's reference in his epic poem Jerusalem to a place that exists somewhere between waking and sleeping, living and dying. The word "beulah" is Hebrew for "married"; this show tells of a woman and man who fall in love and who go to live on an island – but because he only has a birthday every four years, he lives on long after she has died. If it's a love story, it's also a kind of ghost story.

Beulah is charm itself, a sweet treat, which sometimes feels a little cloying. What's intriguing is its form: it's a piece of musical theatre, though not a traditional musical, performed by Jim Harbourne and Ed Wren, who composed the score and play a range of instruments, from penny whistles to the harp. It also engenders a dreamlike state: going to Beulah is not so much like seeing a show as entering into a state of mind or sinking into a vision. It cleverly recreates in the theatre that feeling of being between wakefulness and sleep, and it completely demands that its audience make the imaginative leap and surrender. Blake opined that Beulah really is a "lovely place" – and so it is, provided that you have no aversion to being charmed.